This invention relates to paperboard containers for packaging food products such as frozen entrees, pizza, baked goods, brownies, and the like. Containers of this invention are typically formed from a unitary blank of paperboard or other stiff, bendable, and resilient sheet material. It is known that ovenable food trays may be improved, regarding their anti-sticking properties, by coating their food contacting surface with one or more layers of polymethylpentene, an FDA approved material. This is shown in U.S. Pat. No. 5,002,833 issued to Kinsey et al, dated Mar. 26, 1991. In the formation of an ovenable tray of the type disclosed in the Kinsey patent, it is not necessary to form an overlapped, adhesively secured joint.
The use of a polymethylpentene, food contacting layer in food-containing, folded paperboard containers of conventional design with glued seams, corners or end-flaps has not however been practiced because of the difficulty encountered in making the required overlapped joints. Namely, because of its anti-stick characteristic, it is difficult to adhere a polymethylpentene coated surface with any conventional FDA approved adhesive in forming a container for food. Such adhesives are water based, due to the dangers inherent in solvent based adhesives regarding flammability, exposure of workers to solvent vapors, and potential of food contamination from the solvents. While some FDA approved adhesives are solvent based, their use in food containers would require expensive analytical testing methods/apparatus to insure that no residual solvent was in the adhesive at the time the food was placed in the containers.